1. Field
Apparatuses and methods consistent with exemplary embodiments relate to a directional backlight unit having improved light uniformity and a 3D image display apparatus including the directional backlight unit.
2. Description of the Related Art
Along with the popularity of three-dimensional (3D) movies, technology for 3D image display apparatuses has been researched. 3D image display apparatuses may display 3D images based on binocular parallax. Currently commercialized binocular-parallax 3D image display apparatuses are configured to display 3D images by providing left-eye and right-eye images having different viewpoints to the left and right eyes of viewers. Such 3D image display apparatuses may be classified into glass-required 3D image display apparatuses requiring special glasses and glass-free 3D image display apparatuses not requiring special glasses.
Examples of glass-required 3D image display apparatuses include red-green glasses type 3D image display apparatuses used for movie theaters, and polarizing glasses or liquid crystal shutter glasses type 3D image display apparatuses for TVs. Glass-free 3D image display apparatuses may be classified according to the structures thereof as barrier-type 3D image display apparatuses, lenticular-type 3D image display apparatuses, etc. In addition, glass-free 3D image display apparatuses may be classified according to image forming methods as multi-view rendering 3D image display apparatuses, volumetric 3D image display apparatuses configured to contain all 3D space information and display the information in a 3D space using voxels, integral imaging 3D image display apparatuses capturing images at multiple angles using lenses shaped like compound eyes of insects (flies' eyes) and inversely displaying the images, holographic 3D image display apparatuses, 3D image display apparatuses using directional backlight units, etc.
Directional backlight units may form 3D images by adjusting the output direction of light using gratings. Light propagating in a light guide plate reaches an end of the light guide plate while being totally reflected. However, a relatively large amount of light is output through a propagation start region of the light guide plate, and the amount of light output from the light guide plate decreases in a direction away from the propagation start region of the light guide plate, thereby resulting in poor optical uniformity.